Perhaps the single most important device in modern electronic systems is the MOSFET. Such devices are used not only as transistors but also as passive devices, such as resistances and capacitances. The ability to scale such devices down to ever smaller dimensions has allowed electronic systems to become smaller to the point of enabling many hand-held and pocket-size systems. However, at the current pace of device scaling, it is predicted that planar transistors will soon reach their limits, in terms of minimize size. Further, as these devices get smaller, they increasingly suffer from undesirable short channel effects, such as off-state leakage current, which increases power consumption by the device.
As a result, multiple-gate MOSFETs have become of increased interest, based on their use of multiple gates on multiple surfaces, thereby more effectively suppressing off-state leakage currents. Further, these multiple gates allow enhanced current in the on-state, i.e., the drive current. Such advantages result in lower power consumption and enhanced device performance. Moreover, such non-planar devices are smaller than conventional planar transistors, thereby enabling even higher circuit densities and, therefore, smaller system sizes.
One particular multiple-gate MOSFET that has been developed is a FinFET, in which the conducting channel is disposed around a thin silicon “Fin”, which serves as the body of the device. The dimensions of the Fin establish the effective channel length for the transistor.
Conventional FinFETs are fabricated using silicon over insulator (SOI) techniques. However, such devices often have poor thermal properties, e.g., poor heat dissipation, as well as relatively significant external resistances. Accordingly, an improved FinFET would be desirable.